Isolating SDN Control Traffic with Layer-2 Slicing in 6TiSCH Industrial IoT Networks

Recent standardization efforts in IEEE 802.15.4-2015 Time Scheduled Channel Hopping (TSCH) and the IETF 6TiSCH Working Group (WG), aim to provide deterministic communications and efficient allocation of resources across constrained Internet of Things (IoT) networks, particularly in Industrial IoT (IIoT) scenarios. Within 6TiSCH, Software Defined Networking (SDN) has been identified as means of providing centralized control in a number of key situations. However, implementing a centralized SDN architecture in a Low Power and Lossy Network (LLN) faces considerable challenges: not only is controller traffic subject to jitter due to unreliable links and network contention, but the overhead generated by SDN can severely affect the performance of other traffic. This paper proposes using 6TiSCH tracks, a Layer-2 slicing mechanism for creating dedicated forwarding paths across TSCH networks, in order to isolate the SDN control overhead. Not only does this prevent control traffic from affecting the performance of other data flows, but the properties of 6TiSCH tracks allows deterministic, low-latency SDN controller communication. Using our own lightweight SDN implementation for Contiki OS, we firstly demonstrate the effect of SDN control traffic on application data flows across a 6TiSCH network. We then show that by slicing the network through the allocation of dedicated resources along a SDN control path, tracks provide an effective means of mitigating the cost of SDN control overhead in IEEE 802.15.4-2015 TSCH networks

Evaluation of Feasibility and Impact of Attacks against the 6top Protocol in 6TiSCH Networks

The 6TiSCH architecture has been gaining attraction as a promising solution to ensure reliability and security for communication in applications for the Industrial Internet of Things (IIoT). While many different aspects of the architecture have been investigated in literature, an in-depth analysis of the security features included in its design is still missing. In this paper, we assess the security vulnerabilities of the 6top protocol, a core component of the 6TiSCH architecture for enabling network nodes to negotiate communication resources. Our analysis highlights two possible attacks against the 6top protocol that can impair network performance and reliability in a significant manner. To prove the feasibility of the attacks in practice, we implemented both of them on the Contiki-NG Operating System and tested their effectiveness on a simple deployment with three Zolertia RE-Mote sensor nodes. Also, we carried out a set of simulations using Cooja in order to assess their impact on larger networks. Our results show that both attacks reduce reliability in the overall network and increase energy consumption of the network nodes

The Contiki-NG open source operating system for next generation IoT devices

Contiki-NG (Next Generation) is an open source, cross-platform operating system for severely constrained wireless embedded devices. It focuses on dependable (reliable and secure) low-power communications and standardised protocols, such as 6LoWPAN, IPv6, 6TiSCH, RPL, and CoAP. Its primary aims are to (i) facilitate rapid prototyping and evaluation of Internet of Things research ideas, (ii) reduce time-to-market for Internet of Things applications, and (iii) provide an easy-to-use platform for teaching embedded systems-related courses in higher education. Contiki-NG started as a fork of the Contiki OS and retains many of its original features. In this paper, we discuss the motivation behind the creation of Contiki-NG, present the most recent version (v4.7), and highlight the impact of Contiki-NG through specific examples

Analysis of Distributed and Autonomous Scheduling Functions for 6tisch Networks

The 6TiSCH architecture is expected to play a significant role to enable the Internet of Things paradigm also in industrial environments, where reliability and timeliness are of paramount importance to support critical applications. Many research activities have focused on the Scheduling Function (SF) used for managing the allocation of communication resources in order to guarantee the application requirements. Two different approaches have mainly attracted the interest of researchers, namely distributed and autonomous scheduling. Although many different (both distributed and autonomous) SFs have been proposed and analyzed, a direct comparison of these two approaches is still missing. In this work, we compare some different SFs, using different behaviors in allocating resources, and investigate the pros and cons of using distributed or autonomous scheduling in four different scenarios, by means of both simulations and measurements in a real testbed. Based on our results, we also provide a number of guidelines to select the most appropriate SF, and its configuration parameters, depending on the specific use case

Vulnerabilities of the 6P protocol for the Industrial Internet of Things: Impact analysis and mitigation

The 6TiSCH architecture defined by the IETF provides a standard solution for extending the Internet of Things (IoT) paradigm to industrial applications with stringent reliability and timeliness requirements. In this context, communication security is another crucial requirement, which is currently less investigated in the literature. In this article, we present a deep assessment of the security vulnerabilities of 6P, the protocol used for resource negotiation at the core of the 6TiSCH architecture. Specifically, we highlight two possible attacks against 6P, namely the Traffic Dispersion and the Overloading attacks. These two attacks effectively and stealthy alter the communication schedule of victim nodes and severely thwart network basic functionalities and efficiency, by specifically impacting network availability and energy consumption of victim nodes. To assess the impact of the attacks two analytical models have been defined, while, to demonstrate their feasibility, they have been implemented in Contiki-NG. The implementation has been used to quantitatively evaluate the impact of the two attacks by both simulations and measurements in a real testbed. Our results show that the impact of both attacks may be very significant. The impact, however, strongly depends on the position of the victim node(s) in the network and it is highly influenced by the dynamics of the routing protocol. We have investigated mitigation strategies to alleviate this impact and proposed an extended version of the Minimal Scheduling Function (MSF), i.e., the reference scheduling algorithm for 6TiSCH. This allows network nodes to early detect anomalies in their schedules possibly due to an Overloading attack, and thus curb the attack impact by appropriately revising their schedule

GT-TSCH: Game-Theoretic Distributed TSCH Scheduler for Low-Power IoT Networks

Time-Slotted Channel Hopping (TSCH) is a synchronous medium access mode of the IEEE 802.15.4e standard designed for providing low-latency and highly-reliable end-to-end communication. TSCH constructs a communication schedule by combining frequency channel hopping with Time Division Multiple Access (TDMA). In recent years, IETF designed several standards to define general mechanisms for the implementation of TSCH. However, the problem of updating the TSCH schedule according to the changes of the wireless link quality and node's traffic load left unresolved. In this paper, we use non-cooperative game theory to propose GT-TSCH, a distributed TSCH scheduler designed for low-power IoT applications. By considering selfish behavior of nodes in packet forwarding, GT-TSCH updates the TSCH schedule in a distributed approach with low control overhead by monitoring the queue length, the place of the node in the Directed Acyclic Graph (DAG) topology, the quality of the wireless link, and the data packet generation rate. We prove the existence and uniqueness of Nash equilibrium in our game model and we find the optimal number of TSCH Tx timeslots to update the TSCH slotframe. To examine the performance of our contribution, we implement GT-TSCH on Zolertia Firefly IoT motes and the Contiki-NG Operating System (OS). The evaluation results reveal that GT-TSCH improves performance in terms of throughput and end-to-end delay compared to the state-of-the-art method.Comment: 43rd IEEE International Conference on Distributed Computing System

RIOT and OpenWSN 6TiSCH: Happy Together

International audienceShort development cycles, application-field diversity, and requirements on network size or reliability put an ever increasing strain on Internet of Things (IoT) application developers. Real-time embedded operating systems (RTOS) aim to provide a key set of features, abstractions and services that enable faster development. To fulfill the promise of wire-like communication reliability, wireless standards such as WirelessHART, ISA100.11a and 6TiSCH have been developed and are used in the industry. Keeping these networks synchronized requires precise timing information from the underlying hardware. However, the hardware abstractions of an RTOS do come with an overhead, and the question arises on how these abstractions impact the performance of a complex network stack. To study this, we integrated Open-WSN, a standards-compliant open-source implementation of the 6TiSCH network stack, with RIOT, a prominent open-source RTOS. We compare the minimalistic "bare metal" approach of OpenWSN with RIOT's full-fledged RTOS environment. We study the impact on network performance, power consumption and real-time application properties. On the one hand, we show that using RIOT to execute a 6TiSCH stack does not degrade power consumption or network performance. On the other hand, we demonstrate how RIOT brings improvements on the time it takes to execute application tasks

In-band network telemetry in industrial wireless sensor networks

With the emergence of the Internet of Things (IoT) and Industry 4.0 concepts, industrial applications are going through a tremendous change that is imposing increasingly diverse and demanding network dynamics and requirements with a wider and more fine-grained scale. Therefore, there is a growing need for more flexible and reconfigurable industrial networking solutions complemented with powerful monitoring and management functionalities. In this sense, this paper presents a novel efficient network monitoring and telemetry solution for Industrial Wireless Sensor Networks mainly focusing on the 6TiSCH Network stack, a complete protocol stack for ultra-reliable ultra-low-power wireless mesh networks. The proposed monitoring solution creates a flexible and powerful in-band network telemetry design with minimized resource consumption and communication overhead while supporting a wide range of monitoring operations and strategies for dealing with various network scenarios and use cases. Besides, the technical capabilities and characteristics of the proposed solution are evaluated via a real-life implementation, practical and theoretical analysis. These experiments demonstrate that in-band telemetry can provide ultra-efficient network monitoring operations without any effect on the network behavior and performance, validating its suitability for Industrial Wireless Sensor Networks

Performance Evaluation of Adaptive Autonomous Scheduling Functions for 6TiSCH Networks

The Internet Engineering Task Force (IETF) has recently defined the 6TiSCH architecture to enable the Industrial Internet of Things (IIoT), i.e., the adoption of the IoT paradigm for industrial applications with stringent requirements, in terms of reliability and timeliness. In 6TiSCH networks, the scheduling of communication resources is of paramount importance to meet the application requirements, and many different Scheduling Functions have been proposed to cope with the needs of various applications. Recently, autonomous scheduling has emerged as an efficient and robust approach, as it allows nodes to allocate communication resources autonomously, i.e., without any negotiation with their neighbors, thus avoiding the related overhead. Typically, this is obtained through static resource-allocation algorithms that are not able to adapt to variations in traffic conditions. In this paper, we consider adaptive autonomous scheduling, and compare the performance of three different algorithms in various IIoT scenarios. We investigate their ability to adapt to traffic changes, and evaluate them in terms of performance, resource consumption, and complexity. Based on the results obtained, we also provide a set of guidelines to select the most appropriate Scheduling Function, and its configuration parameters, depending on the specific use case